CN111801878A - Motor vehicle auxiliary unit - Google Patents

Abstract

The invention relates to a motor vehicle auxiliary unit motor (10) having a permanent-magnet motor rotor (14), a motor stator (12), a motor electronics unit (18) and a contact spring (42), wherein the motor stator (12) has a ferromagnetic stator body and has at least one stator winding (24), the motor electronics unit has an outer ground connection (32) and an inner ground contact (40), the outer ground connection (32) is used for electrically connecting the motor electronics unit (18) to an outer vehicle ground (34), the inner ground contact (40) is electrically connected to the outer ground connection (32), wherein the motor electronics unit (18) is electrically connected to the stator winding (24) for controlling the stator winding (24), and the contact spring (42) makes a direct connection between the inner ground contact (40) of the motor electronics unit (18) and the stator body (20) And electrically connecting the contacts.

Description

Motor vehicle auxiliary unit

The invention relates to an electric motor of a motor vehicle auxiliary unit, which is used, for example, for an electric air pump of a motor vehicle (KFZ).

Electric motors of this type include a permanent magnet motor rotor and a motor stator with a ferromagnetic stator body and at least one stator winding. Furthermore, the electric motor has a motor electronics unit which is electrically connected to the stator winding for controlling the stator winding and thereby driving the motor rotor. The electromechanical unit includes an external ground connection so that the electromechanical electronic unit is connected to an external vehicle ground.

Like all electronic equipment, the electric motor also emits electromagnetic interference radiation, which can lead to malfunctions or failures of the electronic equipment in the environment surrounding the electric motor, for example, the motor control electronics of the motor vehicle. For this reason, electronic equipment must meet application-specific regulations regarding electromagnetic compatibility (EMV).

Therefore, the technical problem to be solved by the present invention is to provide a motor of an auxiliary unit of a motor vehicle, which has continuously good EMV performance.

This technical problem is solved by a motor vehicle auxiliary unit electric motor having the technical features of claim 1 .

The motor of the motor vehicle auxiliary unit according to the invention comprises a permanent magnet motor rotor and a motor stator with a ferromagnetic stator body and at least one stator winding. The motor rotor may preferably be a ferromagnetic rotor body with separate permanent magnets. The electronic rotor can alternatively also have a one-piece permanent magnet rotor body.

The motor of the motor vehicle auxiliary unit according to the invention comprises a motor electronics unit which is electrically connected to the stator winding for controlling the stator winding and thereby driving the motor rotor. The motor rotor includes a number of power semiconductors so that the electrical energy used to control the stator windings is rectified. The electromechanical electronic unit is electrically connected to the external vehicle ground via an external ground connection for enabling the power supply to the electromechanical electronic unit. Furthermore, the electromechanical unit has an internal ground contact which is directly electrically connected to the external ground connection via a low-resistance electrical connection.

The motor vehicle auxiliary unit motor according to the invention comprises contact springs which enable a direct, low-resistance electrical connection between the stator body and the internal ground contacts of the motor electronics unit and between the stator body and the vehicle ground . As a result, the stator body can function as an electromagnetic shield, thereby sharply reducing the electromagnetic radiation emitted by the motor, thereby significantly improving the electromagnetic compatibility of the motor. The motor vehicle auxiliary unit motor according to the invention is particularly reliable and durable, even with the use of electrically insulating plastic housings that do not function as electromagnetic shielding, and even at high engine speeds where electromagnetic interference radiation is particularly pronounced to achieve better EMV performance.

Due to the mechanical flexibility of the contact springs, axial movements between the electro-mechanical components and the stator body can be compensated in particular, whereby interruptions of the electrical connection between the internal ground contact and the stator body can be avoided, for example due to motor vibrations or Interruptions caused by fracture of soldered connections during vibrations in electric motors. The mechanically flexible contact spring according to the invention thus enables a particularly reliable electrical connection between the inner ground contact and the stator body.

The stator body of the stator of the electric machine is preferably formed from a laminated core, as a result of which eddy currents in the stator body are minimized. This achieves high efficiency of the electric motor. The individual laminations of the lamination stack are here electrically connected to one another, for example by means of a form-fit connection by means of corresponding punching.

In a preferred embodiment of the invention, the stator has only one single stator winding. This enables an extremely compact and cost-effective embodiment of the electric motor.

The contact spring is preferably a helical spring, which has a high flexibility in the axial direction as well as in the radial direction, so as to be able to compensate for axial and radial movements between the inner ground contact and the stator body. This enables a particularly reliable and permanent electrical connection between the inner ground contact and the stator body.

In a preferred embodiment, the electromechanical electronics have a circuit board on which the internal ground contacts are arranged. The circuit board allows a particularly simple arrangement of electronic components. The circuit board is made of fiber-reinforced plastic, for example, and includes a printed circuit for the electrical connection of each electronic component.

In a particularly preferred embodiment, the inner ground contact is formed by an uninsulated printed circuit region of the printed circuit board, which is electrically connected directly to the outer ground connection. This allows a simple and cost-effective implementation of the internal ground contact, without the need to provide additional contact elements for this purpose.

The contact springs are preferably fastened, for example by solder connections, to the circuit board and only rest on the stator body. This enables a very simple installation of the contact spring. In addition, mechanical damage to the contact spring or its fixing portion due to stress can be avoided by the one-sided fixing of the contact spring. Despite the one-sided fixation, a suitable axial prestressing of the contact springs ensures a reliable electrical connection between the inner ground contact and the stator body.

Embodiments of the invention are described below with reference to the attached drawing, which shows a schematic side view of an electric motor for an auxiliary unit of a motor vehicle according to the invention.

The drawing shows a motor vehicle auxiliary unit electric motor 10 , which is used, for example, in an exhaust pump for a fuel tank of a motor vehicle. Exhaust pumps of this type will operate at a rotational speed of more than 10,000 rpm and thus are particularly prone to generate electromagnetic interference radiation.

The electric motor 10 comprises a housing 11 , which in an embodiment of the invention is made of electrically insulating plastic, a motor stator 12 , a permanent magnet motor rotor 14 with a rotor shaft 16 and a motor electronics unit 18 .

The motor stator 12 comprises a stator body 20 and a single stator winding 24, the stator body 20 being composed of a lamination stack of a plurality of ferromagnetic laminations 22 that are electrically connected to each other.

The electromechanical unit 18 includes a circuit board 28 on which the electromechanical components 30 are arranged. The motor electronics 30 are electrically connected to the stator windings 24 via connecting elements 26 in order to control the stator windings 24 and thereby drive the motor rotor 14 . The electromechanical unit 18 includes an external ground connection 32 which is electrically connected to an external vehicle ground 34 . The circuit board 28 includes a printed circuit 36 which electrically connects the external ground connection 32 to the electromechanical electronics 30 . The printed circuit board 28 includes a non-insulated printed circuit area 38 of the printed circuit 36 , which forms the internal ground contact 40 of the electromechanical unit 18 .

The inner ground contact 40 is electrically connected to the stator body 20 via a contact spring 42, which in the embodiment of the present invention is a coil spring made of a material with high electrical conductivity. The contact spring 42 is fastened to the inner ground contact 40 at the first axial end 44 , for example by means of a soldered connection, and contacts the stator body 20 at the opposite second axial end 46 . The contact springs are preloaded in the axial direction, making it possible to compensate for axial and radial movements between the stator body 20 and the motor electronics unit 18 and thus ensure a reliable electrical connection between the inner ground contacts 40 and the stator body 20 . connect. Furthermore, due to the one-sided fixing of the contact spring 42 , mechanical damage to the contact spring 42 or its fixing can be avoided even in the case of strong movements between the stator body 20 and the electromechanical electronic unit 18 .

The contact spring 40 achieves an electrical potential balance between the stator body 20 and the inner ground contact 40 , and thus between the stator body 20 and the vehicle ground 34 . Therefore, the stator body 20 can function as an electromagnetic shield, thereby significantly improving the EMV performance of the motor 10 .

List of reference signs

10 Motors for motor vehicle auxiliary units

11 Housing

12 Motor stator

14 Motor rotor

16 Rotor shaft

18 Motor electronics unit

20 Stator body

22 Ferromagnetic Laminations

24 Stator windings

26 Connection elements

28 circuit boards

30 Motor electronics

32 External ground connection

34 External vehicle ground

36 Printed Circuits

38 Uninsulated printed circuit areas

40 Internal ground contact

42 Contact spring

44 The first axial end of the contact spring

46 The second axial end of the contact spring

Claims (7)

1. A motor (10) for a motor vehicle auxiliary unit has: a permanent magnet motor rotor (14); an electric motor stator (12) having a ferromagnetic stator body (20) and having at least one stator winding (24); A motor-electronic unit (18) having an outer ground connection (32) and an inner ground contact (40), the outer ground connection (32) being used to enable the motor-electronic unit (32) 18) Electrical connection to an external vehicle ground (34), the internal ground contact (40) to the external ground connection (32), wherein the electromechanical electronic unit (18) is connected to the stator winding (24) is electrically connected for controlling the stator winding (24); and A contact spring (42) enables a direct electrical connection between the inner ground contact (40) of the motor electronics unit (18) and the stator body (20). 2. The motor vehicle auxiliary unit motor (10) according to claim 1, wherein, The stator body (20) is composed of laminations. 3. Motor vehicle auxiliary unit electric motor (10) according to one of the preceding claims, wherein, The stator (12) has only one single stator winding (24). 4. Motor vehicle auxiliary unit electric motor (10) according to one of the preceding claims, wherein, The contact spring (42) is a coil spring. 5. Motor vehicle auxiliary unit electric motor (10) according to one of the preceding claims, wherein, The electromechanical electronic unit (18) has a circuit board (28) on which the internal ground contacts (40) are arranged. 6. The motor vehicle auxiliary unit motor (10) according to claim 5, wherein, The inner ground contact (40) is formed by a non-insulated printed circuit area (38) of the circuit board (28). 7. Motor vehicle auxiliary unit motor (10) according to claim 5 or 6, wherein, The contact spring (42) is fastened on the circuit board (28) and rests on the stator body (20).

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